The purpose of the proposed study is the direct investigation of IgE biosynthesis in the mouse utilizing new methods of assay of humoral and cellular IgE production and specific suppression of this response by treatment of neonatal mice with anti-IgE. The first objective will be to develop specific techniques to quantitate humoral and cellular IgE synthesis utilizing a specific rabbit antiserum to mouse IgE. Total and specific IgE will be quantiated by a galactosidase immunosorbent test. IgE bearing lymphocyteswill be detected by immunofluorescence. IgE antibody producing cells will be determined by the indirect plaque forming cell assay. These procedures will be used to determine host and environmental factors regulating IgE biosynthesis. IgE synthesis will first be investigated in different lymphoid organs and other organs known to contain IgE producing cells such as the lung and gastrointestinal tract. Utilizing this approach, the IgE response will be studied in different strains and age catagories of mice. The effect of laboratory counterparts of environmental factors (such as pertussis and aluminum hydroxide adjuvants) as well as the role of antigen type, size, dose and route of administration in stimulating IgE production will be determined. Mice will be treated with rabbit antiserum to suppress their IgE response. As different time intervals post treatment, the effect of the absence of IgE on the immune response and host defense will be determined. These studies will assess the role of IgE in the mouse and investigate different factors affecting its production on the relationship of these effects to IgE biosynthesis in atopics. Throug such studies it is hoped to further our understanding of IgE synthesis in man.